First-Principles Investigation of Janus MgZnXY (X, Y = O, S, Se, Te; X ≠ Y) Monolayers for Short-Channel Field Effect Transistor

Exploring new two-dimensional materials as the channel of ultrascaled field effect transistors (FETs) is in great demand to sustain Moore's law. Herein, using first-principles calculations, we propose Janus MgZnXY (X, Y & boxH;O, S, Se, and Te; X not equal Y) monolayers and examine their energetic, dynamic, and thermal stability. The electronic band structures reveal that all stable structures are semiconductors with bandgaps ranging from 2.03 to 3.40 eV (HSE06) and extremely high electron mobilities. Inspired by the exceptional intrinsic properties of the MgZnXY family, we investigate the performance of a double-gate n-type field effect transistor (DG-nFET) with a MgZnSSe monolayer as the channel material. It is shown that sub-5 nm gate length MgZnSSe DG-nFETs with suitable underlap length and contacts' doping outperform the International Technology Roadmap for Semiconductors with high-performance (HP) and low-power (LP) standards. It is also revealed that the impressively high on-current of 3620 mu A/mu m and ultralow delay time and power-delay product of 0.064 ps and 0.149 fJ/mu m, respectively, can be achieved for HP MgZnSSe DG-nFET. In addition, we investigate the gate-control ability of the proposed device and show that the structures with electrodes' doping of 1 x 10(13) and 2 x 10(13) cm(-2) can give subthreshold swings down to 73 and 75 mV/dec, respectively. Our results demonstrate that the proposed MgZnXY monolayers have great potential in future competitive short-channel FETs.